The objectives of the proposed research are to adapt single substrate tests for determining bacterial characteristics for use in a semi-automated system and to determine the reliability and reproducibility of the reactions as well as their value in identification of bacteria associated with both healthy and diseased periodontal tissues in man. After preliminary work to determine appropriate concentrations of substrates and inoculum, buffered fermentable substrates and substrates to determine specific enzyme activities will be delivered to wells of microtiter plates. These will be inoculated with dense suspensions of non-growing reference strains of bacteria and reactions determined within 6 hours. Data will be analyzed to determine characteristics of value in identification of various groups of bacteria found in the oral cavity. The resulting systems will be utilized to identify 300 or more bacterial isolates from healthy and diseased periodontal tissues.